MNT: (deps): Bump actions/cache from 2.1.5 to 2.1.6

Bumps [actions/cache](https://github.com/actions/cache) from 2.1.5 to 2.1.6.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2.1.5...v2.1.6)

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/docs-conda.yml

@@ -35,7 +35,7 @@ jobs:
       run: git fetch --depth=1 origin +refs/tags/*:refs/tags/*
 
     - name: Setup conda caching
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ~/conda_pkgs_dir
         key: conda-docs-${{ runner.os }}-${{ matrix.python-version}}-${{ hashFiles('ci/*') }}
@@ -64,7 +64,7 @@ jobs:
       run: echo "::set-output name=dir::$(python -c 'import cartopy;print(cartopy.config["data_dir"])')"
 
     - name: Setup mapdata caching
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       env:
         # Increase to reset cache of map data
         CACHE_NUMBER: 0

.github/workflows/docs.yml

@@ -55,7 +55,7 @@ jobs:
       run: echo "::set-output name=dir::$(pip cache dir)"
 
     - name: Setup pip cache
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ${{ steps.pip-cache.outputs.dir }}
         key: pip-docs-${{ runner.os }}-${{ matrix.python-version }}-${{ hashFiles('ci/*') }}
@@ -82,7 +82,7 @@ jobs:
       run: echo "::set-output name=dir::$(python -c 'import cartopy;print(cartopy.config["data_dir"])')"
 
     - name: Setup mapdata caching
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       env:
         # Increase to reset cache of map data
         CACHE_NUMBER: 0

.github/workflows/nightly-builds.yml

@@ -39,7 +39,7 @@ jobs:
       run: echo "::set-output name=dir::$(pip cache dir)"
 
     - name: Setup caching
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ${{ steps.pip-cache.outputs.dir }}
         key: pip-tests-${{ runner.os }}-${{ matrix.python-version }}-${{ hashFiles('ci/*') }}
@@ -73,7 +73,7 @@ jobs:
 
     - name: Setup mapdata caching
       if: ${{ steps.cartopy-cache.outputs.dir != '' }}
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       env:
         # Increase to reset cache of map data
         CACHE_NUMBER: 0
@@ -140,7 +140,7 @@ jobs:
       run: echo "::set-output name=dir::$(pip cache dir)"
 
     - name: Setup pip cache
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ${{ steps.pip-cache.outputs.dir }}
         key: pip-docs-${{ runner.os }}-${{ matrix.python-version }}-${{ hashFiles('ci/*') }}
@@ -173,7 +173,7 @@ jobs:
       run: echo "::set-output name=dir::$(python -c 'import cartopy;print(cartopy.config["data_dir"])')"
 
     - name: Setup mapdata caching
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       env:
         # Increase to reset cache of map data
         CACHE_NUMBER: 0

.github/workflows/tests-conda.yml

@@ -34,7 +34,7 @@ jobs:
       run: git fetch --depth=1 origin +refs/tags/*:refs/tags/*
 
     - name: Setup conda caching
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ~/conda_pkgs_dir
         key: conda-tests-${{ runner.os }}-${{ matrix.python-version}}-${{ hashFiles('ci/*') }}
@@ -64,7 +64,7 @@ jobs:
       run: echo "::set-output name=dir::$(python -c 'import cartopy;print(cartopy.config["data_dir"])')"
 
     - name: Setup mapdata caching
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       env:
         # Increase to reset cache of map data
         CACHE_NUMBER: 0

.github/workflows/tests-pypi.yml

@@ -49,7 +49,7 @@ jobs:
       run: echo "::set-output name=dir::$(pip cache dir)"
 
     - name: Setup caching
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: ${{ steps.pip-cache.outputs.dir }}
         key: pip-tests-${{ runner.os }}-${{ matrix.python-version }}-${{ hashFiles('ci/*') }}
@@ -100,7 +100,7 @@ jobs:
 
     - name: Setup mapdata caching
       if: ${{ steps.cartopy-cache.outputs.dir != '' }}
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       env:
         # Increase to reset cache of map data
         CACHE_NUMBER: 0